Heat storage system

A heat storage system comprising:

• a heat source that is operable to generate heat and release the heat to a first heat medium;
• a heat storage body that is operable to store the heat released from the heat source via the first heat medium;
• and
• a flow passage through which the first heat medium can flow between the heat source and the heat storage body, wherein
• the heat storage body is operable to change to a first phase in a solid state when a temperature of the heat storage body is lower than or equal to a phase transition temperature, and is operable to change to a second phase in a solid state when a temperature of the heat storage body exceeds the phase transition temperature,
• the heat storage body is operable to store or release heat due to a phase transition between the first phase and the second phase, and
• wherein a mode of operation of the heat storage body is switchable between a heat storage mode in which the heat storage body stores heat of the first heat medium and a heat release mode in which the heat storage body releases the heat stored in the heat storage body to a heat transfer target.